U.S. patent application number 10/791173 was filed with the patent office on 2005-09-22 for method and apparatus for electrical stimulation to enhance lancing device performance.
Invention is credited to Chan, Frank A..
Application Number | 20050209625 10/791173 |
Document ID | / |
Family ID | 34962579 |
Filed Date | 2005-09-22 |
United States Patent
Application |
20050209625 |
Kind Code |
A1 |
Chan, Frank A. |
September 22, 2005 |
Method and apparatus for electrical stimulation to enhance lancing
device performance
Abstract
A lancing device where electrical stimulation is applied to a
skin sampling site prior to making an incision to achieve at least
one of pain masking and bodily fluid engorgement at the site. The
electrical stimulation is supplied by a low current high voltage AC
signal generator in sufficient quantities to produce vasodialation
and/or pain masking.
Inventors: |
Chan, Frank A.; (Sunnyvale,
CA) |
Correspondence
Address: |
Woodard, Emhardt, Moriarty, McNett & Henry LLP
Bank One Center/Tower
Suite 3700
111 Monument Circle
Indianapolis
IN
46204-5137
US
|
Family ID: |
34962579 |
Appl. No.: |
10/791173 |
Filed: |
March 2, 2004 |
Current U.S.
Class: |
606/181 |
Current CPC
Class: |
A61B 5/15113 20130101;
A61B 5/150412 20130101; A61N 1/36021 20130101; A61N 1/3756
20130101; A61B 5/150022 20130101; A61B 5/15117 20130101; A61B
5/150503 20130101; A61B 5/15123 20130101; A61B 5/15121 20130101;
A61B 5/15125 20130101; A61B 5/150106 20130101; A61B 5/150091
20130101; A61B 5/1519 20130101 |
Class at
Publication: |
606/181 |
International
Class: |
A61B 017/14 |
Claims
What is claimed:
1. Apparatus for obtaining a sample of bodily fluid through the
skin, said apparatus comprising: a housing, a plurality of
electrodes on said housing and positioned to contact a site on the
skin, an electrical signal generator for applying electrical energy
to said electrodes, said electrical signal generator supplying
electrical energy in sufficient quantity to stimulate the skin at
said site to accomplish at least one of pain masking and bodily
fluid engorgement at said site, and a skin-lancing device mounted
in said housing for directing a skin-lancing medium against the
skin at said site to form an incision therein subsequent to the
application of said electrical energy.
2. Apparatus as claimed in claim 1 wherein said electrodes are
positioned in an array to surround said site.
3. Apparatus as claimed in claim 2 wherein said skin-lancing medium
is directed through the middle of said electrode array into said
skin.
4. Apparatus as claimed in claim 1 wherein said electrical signal
generator supplies high voltage AC.
5. Apparatus as claimed in claim 4 wherein the quantity of
electrical energy is less for engorgement than pain masking.
6. Apparatus as claimed in claim 5 wherein said electrical energy
is applied to said site for approximately 30 seconds, to produce
bodily fluid engorgement.
7. Apparatus as claimed in claim 6 wherein said electrical power
supply is adapted to apply electrical energy for at least one
minute for pain masking and engorgement.
8. Apparatus as claimed in claim 4 where in the voltage range of
said electrical power supply is from between approximately 10 to 25
kilovolts at low current (i.e. 100 miliamps).
9. Apparatus as claimed in claim 2 wherein said unit has a
plurality of electrode pairs in an array surrounding said site.
10. Apparatus as claimed in claim 1 wherein said apparatus is a
self-contained unit.
11. Apparatus as claimed in claim 10 wherein said electrical signal
generator has an adjustable level of electrical energy.
12. Apparatus as claimed in claim 1 wherein said electrical signal
generator is adapted to adjust the level of electrical energy.
13. Apparatus as claimed in claim 1 further comprising a device
adjacent said skin lancing device for indicating a bodily fluid
parameter
14. Apparatus as claimed in claim 13 further comprising a capillary
passage leading from the skin incision to said bodily fluid
indicator device.
15. A method for obtaining a sample of bodily fluid through the
skin, said method comprising: applying electrical energy to a
sampling site on said skin of sufficient quantity to stimulate the
skin at said site to accomplish at least one of pain masking and
bodily fluid engorgement at said site, and subsequently making an
incision at said site to remove a sample of bodily fluid.
16. A method as claimed in claim 15 wherein said electrical energy
is applied in an array around said site.
17. A method as claimed in claim 15 wherein said electrical energy
is applied in the form of high voltage AC.
18. A method as claimed in claim 17 wherein a lower level of
electrical energy is applied for engorgement.
19. A method as claimed in claim 18 wherein said electrical energy
is applied for approximately 30 seconds for bodily fluid
engorgement.
20. A method as claimed in claim 18 wherein said electrical energy
is applied for at least 60 seconds for pain masking and
engorgement
21. A method as claimed in claim 17 wherein the voltage range is
between approximately 15 and 25 kilovolts.
22. A method as claimed in claim 17 wherein the electrical energy
is adjustable.
23. A method as claimed in claim 15 comprising the further step of
compressing the site subsequent to making an incision for further
enhancing bodily fluid expression.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to devices and methods for
obtaining samples of blood and other fluids from the body for
analysis or processing.
BACKGROUND OF THE INVENTION
[0002] The wide-spread application of devices for extracting
samples of bodily fluids for analysis such as determining blood
glucose level has led to significant activity in the field to
address several problems and issues. These are the problems of pain
when the skin is pierced by a lance and the problem of insuring a
sufficient quantity of blood at the surface to obtain a proper
sample size. Many proposals have been made to achieve these
ends.
[0003] In terms of pain management there are there have been
developments relative to the shape of the lance itself. These have
involved depth of cuts so that the depth is the minimum necessary
to extract a sample. In addition, the rate of incision has been
controlled so that with a faster incision, pain is diminished.
[0004] Other activities have focused on pain masking by using
vibrators and even patient distractions so that a patient is not
focusing on the pain that will be experienced during the
process.
[0005] A second area of effort focuses on stimulating increased
presence of blood so that at least a minimum blood sample size is
collected after lancing for accurate testing. Some research has
focused on ways of palpating the skin to express additional blood,
either manually or by various mechanisms. Other researchers have
proposed using vibration, ultrasonics and other stimulation to
increase blood flow. However, such devices are either too crude and
simplistic or are overly complicated and expensive.
[0006] The above activity is brought into increased focus when
alternate site testing (AST) is adopted to sample bodily fluids
from locations other than the fingers. Both pain minimization and
blood engorgement need to be managed.
SUMMARY
[0007] The invention, in one form, relates to a device for
obtaining a sample of bodily fluid through the skin. The device
comprises a housing and electrodes on the housing positioned to
contact a site on the skin. An electrical signal generator applies
electrical energy to the electrodes in sufficient quantity to
stimulate the skin at the site to accomplish at least one of pain
masking and bodily fluid engorgement at the site. A skin-lancing
device mounted in the housing directs a skin-lancing medium against
the skin at the site to form an incision therein subsequent to the
application of electrical energy.
[0008] In another form, the invention relates to a method obtaining
a sample of bodily fluid through the skin. The method comprises
applying electrical energy to a sampling site on the skin of
sufficient quantity to stimulate the skin at the site to accomplish
at least one of pain masking and bodily fluid engorgement at the
site. Subsequently, an incision is formed at the site to remove a
sample of bodily fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 shows a highly schematic drawing showing the
application of the present invention to a lancing device.
[0010] FIG. 2 shows a perspective view of one set of electrodes and
skin contacting end wall configuration for use in the lancing
device of FIG. 1.
[0011] FIG. 3 shows an alternative array of electrodes and end wall
design for the lancing device of FIG. 1.
[0012] FIG. 4 shows a simplified circuit diagram for the signal
generator shown schematically in FIG. 1.
DESCRIPTION OF THE SELECTED EMBODIMENT
[0013] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiments illustrated herein and specific language will be used
to describe the same. It will nevertheless be understood that no
limitation of the scope of the invention is thereby intended. Any
alterations and further modifications in the described processes,
systems or devices, and any further applications of the principles
of the invention as described herein, are contemplated as would
normally occur to one skilled in the art to which the invention
relates.
[0014] The present invention uses electrical treatment of a skin
sampling site to achieve one or both of pain masking and blood
engorgement before a lancing device causes an incision to be made
for blood sampling.
[0015] Referring to FIG. 1, there is shown a lancing device 10
comprising a housing 12 which may be annular in form. Housing 12
has skin contacting end cap 14 which may take the form shown in
FIG. 2 or FIG. 3 as discussed below. End cap 14 has an end section
16 removably connected to the end 18 of housing 12. Mounted within
housing 12 is a lancet holder 20 connected to a lancet actuator 22.
Lancet actuator 22 is responsive to an operator controlled button
24 through interconnection 26 to cause lancet carrier 22 to
displace a lancet 28 to the left as viewed in FIG. 1 to pierce the
skin adjacent to device 10. It is also possible to use the pressure
of cap 14 against a skin site through an interconnection (not
shown) with lancet actuator 22 to displace lancet 28. Lancet
actuator 22 is adapted to have a controlled rate of displacement
and depth of penetration to provide optimum withdrawal of bodily
fluid such as blood. Lancet 28 is removable so that it may be
disposed in appropriate fashion after a test is completed. Although
making a mechanical incision is described for piercing the skin, it
should be apparent that other mechanisms for making an incision,
such as a laser, could be used with the present invention.
[0016] Lancet actuator 22 may take one of many different forms to
achieve a controlled rate of displacement and penetration depth for
the lancet 28. Lancet actuator 22 may be mechanical in form using a
spring-like device. It may also be electrically or pneumatically
actuated. As herein shown, a capillary passage 35 leads from the
mouth of passage 34 adjacent the incision of lancet 28 to a sensor
37 which gives an indication of bodily fluid parameter or condition
through optical read-out 39. Alternatively, lancet 28 may to pierce
the skin so that a sufficient quantity of blood may accumulate on
the skin for application to a test strip (not shown). It should be
noted that to those skilled in the art, the unit may be used to
collect blood samples through the lancet 28 and provide still
another way to integrate the testing process.
[0017] The advantages and features of the present invention will be
seen to be equally applicable to the range of devices used to
sample blood for glucose measurement and other applications. More
specifically, the invention would be applicable to devices that
sample and analyze the blood in a single unit.
[0018] In accordance with the present invention, the lancing device
cap 14 has a plurality of electrodes 30 and 32 grouped within sets.
The electrodes 30 and 32 are positioned in an array around the
periphery of an opening 34 for lancet 28. As described below, the
cap 14 may take the form shown in FIG. 2 or in FIG. 3. The
electrode sets 30 and 32 may be deployed on the head in a variety
of arrays to achieve the objectives of the present invention. They
may be positioned in a random fashion with pairs positioned
adjacent one another without any specific orientation.
Alternatively, the pairs may be arranged in circumferential fashion
around the opening 34. A further orientation may be in radial
arrays. Based on present experimentation, the random orientation of
the electrodes allowed achievement of the objectives of the
invention. It should be apparent to those skilled in the art that
the electrodes may be oriented other than in the random fashion and
still achieve objectives of the present invention.
[0019] As shown in FIG. 1, the electrodes 30 and 32 are connected
by lines 36 and 38 to a signal generator and controller 40. Signal
generator 40 is supplied with electrical power from a power source
such as a battery 42 via lines 44 and 46. As shown in FIG. 4,
signal generator 40 comprises an integrated circuit (IC) oscillator
70 having input leads 72 and 74. Oscillator 70 provides an output
on terminal 3 via resistor 76 to the gate of a transistor 78.
Transistor 78 is connected between line 44 and 46 on the input to a
step up transformer 80. Output terminal 7 of oscillator 70 provides
an input to a variable resistor 82 so as to control the frequency
of oscillator 70. The output side of transformer 80 is connected to
output leads 36 and 38 which lead to the electrodes 30 and 32.
Capacitors 84 and 86 provide smoothing of the output wave. The
transistor 78 acts to pass current through the input side of
transformer 80 in approximately a square wave. The transformer 80
increases the voltage output to an equivalent square wave on the
output side. Capacitor 86 smoothes the wave form so that it ends up
being a high voltage AC waveform. Variable resistor 82 is
adjustable by means of an operator-manipulated knob 48 via an
appropriate connection indicated by dashed line 50.
[0020] Signal generator 40, as illustrated, is of a type that
generates a high voltage AC wave. The voltage level can be
approximately from 10 to 25 kilovolts. The frequency preferably is
20 Hz. The signal generator controller 44 can be adapted to control
the signal generator 40 through a range of frequencies, voltages
and at low current (i.e. 100 miliamps) as appropriate for the
applications described below.
[0021] The present invention relies on the principle of electrical
treatment prior to the lancing of the skin to accomplish at least
one of pain masking and bodily fluid or blood engorgement.
[0022] In one aspect, the electrical pulses stimulate the
peripheral terminals of sensory neurons in the body, which cause
the release of bioactive substances. These substances for the most
part are neuropeptides; substance P and calcitonian gene related
peptide. They in turn act on target cells in the periphery of the
applied area such as masked cells, immune cells and smooth muscle
producing inflammation. This is characterized by redness and
warmth, an indication of vasodialation. This phenomenon is known as
neurogenetic inflammation.
[0023] It has been determined that application of electrical
stimulus for a period of approximately 30 seconds will produce
vasodialation. Accordingly, after the application of the electrical
energy, the lancet 28 is actuated to pierce the skin and produce a
quantity of blood which is enhanced by the pretreatment of the
surface to produce vasodilatation. In tests outlined in table 1,
there is as shown a 77% increase in average blood volume and a 16%
increase in the success rate to obtain 0.75 microliters of a
sample. For this test, the voltage level was 16 kilovolts at 20 Hz.
It should be apparent to those skilled in the art that the
electrical parameters set forth in this description are for
illustration purposes only based on current investigations and are
not to be construed or interpreted as in any way limiting the range
of electrical parameters applied within the scope of the present
invention.
1 TABLE 1 Blood Collected (.mu.L) W/O With Test Stimulation
Stimulation Avg. (.mu.L) 0.82 1.45 Median (.mu.L) 0.91 1.36 StDev
0.50 0.69 Success Rate 67% 83% at 0.75 .mu.L
[0024] The success rate can further be enhanced by using an
expression cap shown in FIG. 2 to permit mechanical compression of
the skin site subsequent to lancing. The cap 14 has a plurality of
electrode pairs 30 and 32 on a skin contacting face 52 in an array
around central opening 34 through which the lancet 28 extends when
it is actuated. As shown in FIG. 2, skin contacting face 52 is
curved in a negative sigmoid shape with an annular concave section
56 leading from opening 34 to an annular convex section 58. The
purpose of this configuration is to allow application of the skin
contacting face 52 to the skin site that has been lanced to force
bodily fluids such as blood to the incision point in sufficient
quantity to obtain a sample for blood analysis.
[0025] In order for electrical stimulation to be used to mask pain,
the electrical energy is applied for a longer duration prior to
making the incision on the skin. This electrical power can be used
through the same electrode pairs shown in FIGS. 1 and 2 or it may
be as embodied in the device of FIG. 3 having a flat faced skin
contacting cap 60 with a plurality of electrode pairs 62 and 64
positioned to generally surround a central opening 66 for the
lancing device. The head 60 is connected to a housing 68 containing
the elements shown in schematic fashion in FIG. 1. As is the case
with FIGS. 1 and 2, the electrode pairs 62, 64 may be oriented in
random, circumferential, or radial fashion.
[0026] Using either array, the electrodes deliver electrical
stimulation to the area to be lanced. This electrical stimulation,
depending upon its nature and character, stimulates the sensory
neutrons which manipulate the transmission of signals of afferent
information to the spinal cord. Electrical stimulation can target
the A-delta and C-fibers which deplete neuropeptides content in the
terminal ends of the fibers or target the A-beta fiber causing an
abundance of signals to be released. The type of outcome is
dependent upon the type and intensity of the electrical stimulus
such as pulse rate and duration of applied stimulus. This prevents
the neuron's ability to transfer information to the central nervous
system with respect to trauma or pain to tissues. The stimulus may
also target A-beta fibers, which causes an abundance of
neuropeptides being released. A-beta fibers are associated with the
detection of pressure. As the lancing occurs, the signals
transmitted by the A-delta and C-fibers are clouded by the
abundance of A-beta fiber signals. This phenomenon tends to reduce
the sensitivity of neociceptive pain. To insure adaptability to as
many users as possible because of different individual stimulation
thresholds, the device is adjustable for the intensity and pulse
rate.
[0027] Table 2 shows the pain rating with and without electrical
stimulation. The electrical stimulation was at 20 Hz for at least
60 seconds prior to lancing. A reduction and/or increase in
tolerance of pain were achieved with electrical stimulation. It
should be apparent to those skilled in the art that the parameters
set forth in this description are for illustration purposes only
based on current investigation and are not to be construed or
interpreted as in any way limiting the range of electrical
parameters applied within the scope of present invention.
2 TABLE 2 Electrical Stimulus - Pain Rating Site Parameter Without
With Forearm 16 kilovolts ac, 1 0 20 Hz Finger 20 kilovolts ac, 20
2 2* Hz 2*: Pain intensity of 2 but much more tolerable pain
[0028] When the device is intended to be used for both pain masking
and engorgement of bodily fluids, the electrical stimulation is
applied for approximately 60 seconds and above. After 30 seconds
the engorgement of the site with blood is achieved and after
approximately 60 seconds the pain masking is realized. Once the
pain masking is achieved, the lancing device is fired to lance the
skin. Subsequent to lancing, the skin contacting surface 52 may be
employed to express bodily fluid or blood from the incision for
application to a test strip. Alternatively, different forms of
lancing devices may be used which extract a sample for delivery to
another test device.
[0029] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiment has been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
* * * * *